Speaking as a WHM main , i play only monk on off class when i'm really bored, I do like to stance dance now and then, but a few factors come into it:

1) Can I keep up with the healing needed on the main tank/other players easily?
2) Have I placed cleric stance and my dps abilities somewhere very comfortable and natural to get to them, without detracting from the comfortable access of my heal abilities?
3) Are we in a very high damage phase, or is the tank slightly undergeared or underskilled?

There are a few other factors , but those are what I can think of off the top of my head. If the answer to any of those is no, I don't dps. And I don't allow anyone to make me feel uncomfortable for not dpsing. My role is a healer. I won't as the paladin to use his (godsawful) cure. I won't ask the summoner to rez (although it's nice when they do!). I expect everyone to play a role to the way they enjoy it/the best of their abilities, and won't expect anything less of myself.

Now, that aside, if you do want to stance-dance, don't macro it mate. Your gonna want to have control instantly of when it's on and when it's off. The advice about hitting it before it's off GCD is a good one. But yeah, you want to know you can get straight back into full healing output instantly, which isn't really possible if it's macro'd up. Or, not possible that i know of or am comfortable with xD

Hopefully that helped a bit, good luck to you mate!